This invention relates generally to defibrillator systems with implantable cardiac leads and particularly implantable cardiac defibrillator leads and methods for the transvenous implantation of objects into the pericardial space of patients.
There are large numbers of patients suffering from severe ischemic heart disease having arterial blockage that places them at risk for life-threatening ventricular arrhythmias. To minimize the chance of death for those patients, there has been a long-felt need in the medical community for a portable but reliable defibrillator unit that could accompany the patients. There has been another long-felt need in the medical community for a defibrillator system that could detect the onset of any arrythmia and automatically defibrillate the patient.
Unfortunately, while defibrillator hardware technology has advanced significantly, there have been serious shortcomings in defibrillator lead electrode design that have inhibited development of automatic portable defibrillators. First, ideal positioning of defibrillator leads now requires a theracotomy and many candidates for an automatic defibrillator are not good candidates for massive chest surgery.
Known transvenously implantable endocardial leads used in pacer systems have adequate electrode surface area for transferring the large quantities of electrical energy used during defibrillation, but they can undesirably cause severe thermal burns to the patient as well as cause high defibrillation thresholds or large volume gas bubbles in the patient's cardiovascular system, if they are used for defibrillation.
External defibrillator leads are not energy efficient because large amounts of energy are dissipated by body tissue between the skin surface and the endocardium. Electrodes optimally inserted in the pericardial space over the right and left ventricles would presumably minimize power consumption and allow development an implantable defibrillator system carried by the patient in the same manner as a cardiac pacer.
It is an additional object of the present invention to devise a method for transvenous implantation of an object, such as a defibrillator system cardiac lead, into the pericardial space of a patient.